/*
 * Copyright 2012-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.web.servlet;

import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.ScannedGenericBeanDefinition;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.core.type.filter.TypeFilter;
import org.springframework.util.Assert;

import java.lang.annotation.Annotation;
import java.util.HashMap;
import java.util.Map;

/**
 * Abstract base class for handlers of Servlet components discovered via classpath
 * scanning.
 *
 * @author Andy Wilkinson
 */
abstract class ServletComponentHandler
{

    private final Class<? extends Annotation> annotationType;

    private final TypeFilter typeFilter;

    protected ServletComponentHandler(Class<? extends Annotation> annotationType)
    {
        this.typeFilter = new AnnotationTypeFilter(annotationType);
        this.annotationType = annotationType;
    }

    TypeFilter getTypeFilter()
    {
        return this.typeFilter;
    }

    protected String[] extractUrlPatterns(String attribute, Map<String, Object> attributes)
    {
        String[] value = (String[]) attributes.get("value");
        String[] urlPatterns = (String[]) attributes.get("urlPatterns");
        if (urlPatterns.length > 0)
        {
            Assert.state(value.length == 0, "The urlPatterns and value attributes are mutually exclusive.");
            return urlPatterns;
        }
        return value;
    }

    protected final Map<String, String> extractInitParameters(Map<String, Object> attributes)
    {
        Map<String, String> initParameters = new HashMap<String, String>();
        for (AnnotationAttributes initParam : (AnnotationAttributes[]) attributes.get("initParams"))
        {
            String name = (String) initParam.get("name");
            String value = (String) initParam.get("value");
            initParameters.put(name, value);
        }
        return initParameters;
    }

    void handle(ScannedGenericBeanDefinition beanDefinition, BeanDefinitionRegistry registry)
    {
        Map<String, Object> attributes =
                beanDefinition.getMetadata().getAnnotationAttributes(this.annotationType.getName());
        if (attributes != null)
        {
            doHandle(attributes, beanDefinition, registry);
        }
    }

    protected abstract void doHandle(Map<String, Object> attributes, ScannedGenericBeanDefinition beanDefinition,
                                     BeanDefinitionRegistry registry);

}
